In medicine, a chronic condition can be distinguished from one that is acute (recent in onset); additionally, a recurrent condition can relapse repeatedly, with periods of remission in between.

The non-communicable diseases are also usually lasting medical conditions but are distinguished by their non-infectious causes. In contrast, some chronic diseases, such as HIV/AIDS, are caused by transmissible infections.

In the United States 25% of adults have at least two chronic conditions.[1] Chronic diseases constitute a major cause of mortality, and the World Health Organization (WHO) attributes 38 million deaths a year to non-communicable diseases.[2]

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Chronic conditions have often been used to describe the various health related states of the human body such as syndromes, physical impairments, disabilities as well as diseases. Epidemiologists have found interest in chronic conditions due to the fact they contribute to disease, disability, and diminished physical and/or mental capacity.[3]

For example, high blood pressure or hypertension is considered to be not only a chronic condition itself but also correlated to diseases such as heart attack or stroke. Additionally, some socioeconomic factors may be considered as a chronic condition as they lead to disability in daily life. An important one that public health officials in the social science setting have begun highlighting is chronic poverty. [4][5]

The list below includes these chronic conditions and diseases:

In 2015 the World Health Organisation produced a report on non-communicable diseases, citing the four major types as:[6]

While risk factors vary with age and gender, most of the common chronic diseases in the US are caused by dietary, lifestyle and metabolic risk factors that are also responsible for the resulting mortality.[8] Therefore, these conditions might be prevented by behavioral changes, such as quitting smoking, adopting a healthy diet, and increasing physical activity. Social determinants are important risk factors for chronic diseases.[9]Social factors, e.g., socioeconomic status, education level, and race/ethnicity, are a major cause for the disparities observed in the care of chronic disease.[9] Lack of access and delay in receiving care result in worse outcomes for patients from minorities and underserved populations.[10] Those barriers to medical care complicate patients monitoring and continuity in treatment.

In the US, Minorities and low-income populations are less likely to access and receive preventive services necessary to detect conditions at an early stage.[11]

The majority of US health care and economic costs associated with medical conditions are for the costs of chronic diseases and conditions and associated health risk behaviors. Eighty-four percent of all health care spending in 2006 was for the 50% of the population who have one or more chronic medical conditions (CDC, 2014).

A growing body of evidence supports that prevention is effective in reducing the effect of chronic conditions; in particular, early detection results in less severe outcomes. Clinical preventive services include screening for the existence of the disease or predisposition to its development, counseling and immunizations against infectious agents. Despite their effectiveness, the utilization of preventive services is typically lower than for regular medical services. In contrast to their apparent cost in time and money, the benefits of preventive services are not directly perceived by patient because their effects are on the long term or might be greater for society as a whole than at the individual level.[12]

Therefore, public health programs are important in educating the public, and promoting healthy lifestyles and awareness about chronic diseases. While those programs can benefit from funding at different levels (state, federal, private) their implementation is mostly in charge of local agencies and community-based organizations.[13]

Studies have shown that public health programs are effective in reducing mortality rates associated to cardiovascular disease, diabetes and cancer, but the results are somewhat heterogeneous depending on the type of condition and the type of programs involved.[14] For example, results from different approaches in cancer prevention and screening depended highly on the type of cancer.[15] The rising number of patient with chronic diseases has renewed the interest in prevention and its potential role in helping control costs. In 2008, the Trust for America's Health produced a report that estimated investing $10 per person annually in community-based programs of proven effectiveness and promoting healthy lifestyle (increase in physical activity, healthier diet and preventing tobacco use) could save more than $16 billion annually within a period of just five years.[16]

In the United States, nearly one in two Americans (133 million) has at least one chronic medical condition, with most subjects (58%) between the ages of 18 and 64.[18] The number is projected to increase by more than one percent per year by 2030, resulting in an estimated chronically ill population of 171 million.[18] The most common chronic conditions are high blood pressure, arthritis, respiratory diseases like emphysema, and high cholesterol.

According to research by the Centers for Disease Control and Prevention, chronic disease is also especially a concern in the elderly population in America. Chronic diseases like stroke, heart disease, and cancer were among the leading causes of death among Americans aged 65 or older in 2002, accounting for 61% of all deaths among this subset of the population.[19] While the majority of chronic conditions are found in individuals between the ages of 18 and 64, it is estimated that at least 80% of older Americans are currently living with some form of a chronic condition, with 50% of this population having two or more chronic conditions.[19] The two most common chronic conditions in the elderly are high blood pressure and arthritis, with diabetes, coronary heart disease, and cancer also being reported among the elder population.[20]

In examining the statistics of chronic disease among the living elderly, it is also important to make note of the statistics pertaining to fatalities as a result of chronic disease. Heart disease is the leading cause of death from chronic disease for adults older than 65, followed by cancer, stroke, diabetes, chronic lower respiratory diseases, influenza and pneumonia, and, finally, Alzheimer’s disease.[19] Though the rates of chronic disease differ by race for those living with chronic illness, it is interesting to note that the statistics for leading causes of death among elderly are nearly identical across racial/ethnic groups.[19]

Chronic illnesses cause about 70% of deaths in the US and in 2002 chronic conditions (heart disease, cancers, stroke, chronic respiratory diseases, diabetes, Alzheimer’s disease, mental illness and kidney diseases) were 6 of the top ten causes of mortality in the general US population.[21] In the United States, 90% of seniors have at least one chronic disease, and 77% have two or more chronic conditions.[22]

Chronic diseases are a major factor in the continuous growth of medical care spending.[23] Healthy People 2010 reported that more than 75% of the $2 trillion spent annually in US medical care are due to chronic conditions; spending are even higher in proportion for Medicare beneficiaries (aged 65 years and older).[11] Spending growth is driven in part by the greater prevalence of chronic illnesses, and the longer life expectancy of the population. Also improvement in treatments has significantly extended the life spans of patients with chronic diseases but results in additional costs over long period of time. A striking success is the development of combined antiviral therapies that led to remarkable improvement in survival rates and quality of life of HIV-infected patients.

In addition to direct costs in health care, chronic diseases are a significant burden to the economy, through limitations in daily activities, loss in productivity and loss of days of work. A particular concern is the rising rates of overweight and obesity in all segments of the US population.[11]Obesity itself is a medical condition and not a disease, but it constitutes a major risk factor for developing chronic illnesses, such as diabetes, stroke, cardiovascular disease and cancers. Obesity results in significant health care spending and indirect costs, as illustrated by a recent study from the Texas comptroller reporting that obesity alone cost Texas businesses an extra $9.5 billion in 2009, including more than $4 billion for health care, $5 billion for lost productivity and absenteeism, and $321 million for disability.[24]

MEDICC Review theme issue on Confronting Chronic Diseases With longer life expectancies in most countries and the globalization of "Western" diets and sedentarism, the main burden of disease and death from these conditions is falling on already-disadvantaged developing countries and poor communities everywhere.